A vehicular air conditioning device used in an automobile and the like includes a heater core which is a heat exchanger for heating, an evaporator which is a heat exchanger for cooling, an air mixing space for mixing warm air that has passed through the heater core and cool air that has passed through the evaporator, and an air mixing damper for changing a mixing ratio between the warm air and cool air in the air mixing space. As an example of such a device, there is known a vehicular air conditioning device disclosed in Patent Document 1 below.
The vehicular air conditioning device disclosed in Patent Document 1 includes an air flow rate adjustment door, which is provided between a warm air passage communicated with the heater core and a cool air passage communicated with the evaporator. Furthermore, the air flow rate adjustment door includes an adjustment door part disposed on the evaporator side, and an auxiliary door disposed on the heater core side, with respect to a rotating shaft. Each of the adjustment door part and the auxiliary door defines a channel together with case wall surfaces respectively facing the adjustment door part and the auxiliary door.
When the air flow rate adjustment door pivots on the rotating shaft, the adjustment door part adjusts the flow rate of the cool air from the evaporator, while the auxiliary door controls the flow rate of the warm air from the heater core. Specifically, the air flow rate adjustment door is made possible to appropriately adjust its pivoting amount between the maximum heating state and the maximum cooling state. In the maximum heating state, the adjustment door part intercepts the cool air from the evaporator so that the warm air from the heater core is maximized. In the maximum cooling state, the auxiliary door intercepts the warm air from heater core so that the cool air from the evaporator is maximized.
For the vehicular air conditioning device configured as described above, it is necessary to suppress inadvertent interchange of heat between the heater core and the evaporator in view of enhancing thermal efficiency.